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        <div style="margin: 0px 10px 0px 10px" class="smalltext">Apache Struts 2 Documentation</div>
        <div style="margin: 0px 10px 8px 10px"  class="pagetitle">S2-011</div>

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            <div id="ConfluenceContent"><h2 id="S2-011-Summary">Summary</h2>

<p>
</p><p>Long request parameter names might significantly promote the effectiveness of DOS attacks</p>

<div class="table-wrap"><table class="confluenceTable"><tbody><tr><th colspan="1" rowspan="1" class="confluenceTh"><p> Who should read this </p></th><td colspan="1" rowspan="1" class="confluenceTd"><p> All Struts 2 developers </p></td></tr><tr><th colspan="1" rowspan="1" class="confluenceTh"><p> Impact of vulnerability </p></th><td colspan="1" rowspan="1" class="confluenceTd"><p> Denial-of-Service attacks </p></td></tr><tr><th colspan="1" rowspan="1" class="confluenceTh"><p> Maximum security rating </p></th><td colspan="1" rowspan="1" class="confluenceTd"><p> Important </p></td></tr><tr><th colspan="1" rowspan="1" class="confluenceTh"><p> Recommendation </p></th><td colspan="1" rowspan="1" class="confluenceTd"><p> Developers should upgrade to <a shape="rect" class="external-link" href="http://struts.apache.org/download.cgi#struts2341">Struts 2.3.4.1</a> </p></td></tr><tr><th colspan="1" rowspan="1" class="confluenceTh"><p> Affected Software </p></th><td colspan="1" rowspan="1" class="confluenceTd"><p> Struts 2.0.0 - Struts 2.3.4 </p></td></tr><tr><th colspan="1" rowspan="1" class="confluenceTh"><p> Original JIRA Tickets </p></th><td colspan="1" rowspan="1" class="confluenceTd"><p> <a shape="rect" class="external-link" href="https://issues.apache.org/jira/browse/WW-3860">WW-3860</a> </p></td></tr><tr><th colspan="1" rowspan="1" class="confluenceTh"><p> Reporter </p></th><td colspan="1" rowspan="1" class="confluenceTd"><p> Johno Crawford </p></td></tr><tr><th colspan="1" rowspan="1" class="confluenceTh"><p> CVE Identifier </p></th><td colspan="1" rowspan="1" class="confluenceTd"><p> CVE-2012-4387 </p></td></tr></tbody></table></div>


<h2 id="S2-011-Problem">Problem</h2>

<p>Request parameters handled by Struts 2 are effectively treated as OGNL expressions. A possible DOS attacker might craft requests to a Struts 2 based application with extremely long parameter names. OGNL evaluation of the parameter name then will consume significant CPU cycles, thus promoting the effectiveness of the DOS attack.</p>

<h2 id="S2-011-Solution">Solution</h2>

<p>As of Struts 2.3.4.1, parameter name length is limited to a maximum of 100 characters. This configuration may be customized by providing the newly introduced parameter "paramNameMaxLength" to the ParametersInteceptor configuration.</p>

<p>Thanks to Johno Crawford for the provided patch.</p>

<p>Please upgrade to&#160;<a shape="rect" class="external-link" href="http://struts.apache.org/download.cgi#struts2341">Struts 2.3.4.1</a>.</p></div>
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